Radio telephone receiver



Dec, 6, 1927.

M. L. MARTus ET AL RADIO TELEPHONE RECEIVER Filed May 16, 1923 2 Sheets-Sheet l BY Jdmes GROSS A TTORNEYS.

Dec. 6, 1927. 0 1,651,531

M L. MARTUS ET AL RADIO TELEPHONE RECEIVER Filed May 16, 1923 2 Sheets-Sheet 2 BY and (71 185 6. R055 Patented Dec. 6, 1927.

1,651,531 PATENT o F1cE.*I

MARTIN L. menus, or WOODBURY, AND EDMUND H. BECKER AND JAMES G. Ross, E

ATERBURY, CONNECTICUT.

nnnro TELEPHONE RECEIVER.

Application filed May 16,

This invention relates to sound receiving devices, articularly for use in the reception of sound generated by the vibrating diaphragms of telephone receivers used in con- 5 nection with radio receiving apparatus.

'It is desirable when tuning in a distant station, or during the reception of a :radio concert to use the full amplification of the receiving set by plugging in the ear phones in the last stage, but owing to the severe strain on'the auditory nerve connecting with the tympanic membrane ofthe ear, due to howling and static, a loud speaker is generally used to reproduce the sound. This however is unsatisfactory,becauseof the great sound waves being propagated by molecular motion, the particles of the air which fill the cavity of the ear are moved forward each impinging on that immediately before it and then rebounding,finally being drivenagainst the tympanic membrane, the vibration of which is transmitted to the auditory nerve,

and thence to the brain,;which,takescognn zance of the sensation. By this'alternate movement of advance and rebound, the'air is alternatelycondensed and'rarefied, causing a severe strain on the eardrum, due to this unnatural method of applying mechanical vi- I brations directly to the ear, without sufficient air intervening to cushionv the hammering blows of the particles of air. Periodic vibrations always yield musical sounds, being 40 smooth and agreeable to the car, while onthe other hand, noises, or non-periodic vibra-- tions, produce on the tympanic membrane a kind of jolting sensation of irregularly recurring shocks.

painfully, just as a flickering light. gives rise to painful sensationin the nerves of sight.

5'0 itance, and it is upon this principle, thatour invention is based;

blev to the reception of radio communications, a loud speaker may ibeused, sufficient air in- 65 tervening t0', mll0W tl16 sound andieliininate A noise thus affects the auditor y nerve- 1923. Serial No. 639,263.

all'strain on thetympanic membrane of the ear. The objections to loud speakers are however innumerable, some of which may be mentioned as follows: the first cost of the receiving set equipped with sufiicient amplification to operate a loud speaker-the excessive amplification of static and hissing me chaical noises -the ideal atmospheric condi tions necessaryto operate properly-rand the inherent metallic sound which is present," even under the very best circumstances.

We have discovered that by supplying a tube, such as rubber, to conduct the sound 7 from the receiver daphragm to the eardrum,

all of the advantages of a loud speaker are obtained, with the added advantages of increasing the range of the receiver by reducing interfering noises, mellowing the sound and eliminating theo metallic' noises of the diaphragm, thus allowing use of full amplification of the receiving set tobe applied directly to the ears. This is principally'due to the cushioning effect of the column of air contained in the tube.

The, law that intensity of sound decreases does not apply to the case of tubes. v The sound waves in that case are not'propagated in the form ofincreasing concentric spheres, and due to the smooth, uniform and u'nobstructed inner wallof the tube, sound waves can be transmitted to a great distan'cewith out any perceptible alteration or reduction. We have also found that sound waves of high frequencies are propagated in tubes less easily than those of audio frequencies. This condition makes our invention particularly adapted for radio reception. f

An object of. the invention therefore, is to provide a sound receiving device,-especially for radio receptiomha'ving tubes for conducting the sound from the diaphragm of the receiver to the ears of the listeners.

- A further object is to provide a listenin device which may be used with comfort and convenience, as distinguished from the present head-phones, which impose approximatel-y one pound of dead weight on thehead of the user, and cannot be used whena hat is w.orn,or a coifi'ure in the case of women.

danger from lightning, this device being in the nature .of-an; insulator. Also I static noisesofhigh intensity, which are very injurious to the ears are made harmless by the v V still further" object is to eliminate the If the atmospheric conditions are favora- 80 in proportion to the square of the distance, I

cushioning effect of. the column. of. air con tained in the tube.

Another object is to provide a construction by which the vib 'ations at each side of. the. diaphragm oi. the receiver are utilized.

Still another object is to provide means by which the tubes may be used for Querying; communications directly from the speaker to the listeners, as when receiving; broadcasting in a large hall or church, such communication being auxiliary to the" radio conduction.- This method is especially advantageous for deaf persons.

With the above and other objects inview, embodiments of our invention are shown in the accompanying drawings and these em;- bodiments Willi be hereinafter more fully described with reference thereto and the invention will be finally pointed: outrin the claims.

In the drawings: i

Fig. 1. is a, perspective view. showing a listening device according to oneembodiment ofi our invention a Fig. 2 is a plan viewof a modificatiom in which av single ear phone is provided with an extension according to our invention, to form a head-set;

Fig. 3 is a perspective view of a: radio: receiving cabinet provided with astill hirthei modification, in: which a single loudspeaker within the set is provided with in series of individual sound tubes, according to our invention; i

Fig. 4 is a plan viewthe device;

Fig. 5 is :1 perspective view of at loud speaker, and in which the sound chamber is provided with a series of outlets for com necting; sound tubes according to our invention; i i

Fig. 6 is a perspective view of a loud speaker; provided with a further lnodiiicar tion of our device; and g:

Fig. T is a sectional view of a still i urther modification, in which the diaphragm ofthe loud s eaker is provided with soundoutlets at eaci side. a

Similar reference characters indicate cormember 24, to which a pair oil? branch tubes 25* and 26 are connected, these tubes being provided at their ends with car pieces 27 and 28 of such size as tocover the earsiand rest against the sides of the head. Theedges of the ear-pieces are rounded and projected. in a manner toconform to the top of: the can, the depth of the concavity at the inner side being. proportioned to: bridge the earwandi relieve it of all lateral pressure; A bowed spring wire 29 is connected at. its coiled ends 30 and 31 to the tubes 25 and 26 for the purpose of holding the ear pieces in yieldable engagement with the ears of the user.

In order to enable the listeners to modulate on cutoifli the sound in their individual tubes a modulating device is provided adjacent the! Y-ronnection, consisting of a spring clamp portion 33 adapted to be clipped over the end of the Y-connection, wlfltll a. ring? porticn I'l -l eniibracingthc rubber tube adjacent the connection and provided: witlb a set-= screw 35,. which may be :uljustnbly pressed: into engagement with the tube b0 modulate: orcut oll'rthe sound. a

By mounting receivers to: whicln the tube 9.3- may be connected, on the panel. one he ceiving set tlielcngth ofthe connectingwiresa is reduced to a 1ninimum,.a1uftasa. number of listeners may be accommodated wiblr thesingldpuir of IfGCGiVGI'Sti/lIB first cost of the set is. considerably reduced; It has found that accommodnitingboth.ears of: eight. listeners from one rcceiver does not percep tibly reduce the intensity of the soundi;

In- Fig. 2 we have illustrated a type (it; receiver,- according to our invention,- by means of which a single receiver 36 isenn plcyed, and is adapted to be engaged directly witli one earof the listener, in the usuali way to receive the vibrations from: one Slllfl. of the diaphragm. The air space at theother side of the i diaphragm is= conneetedyby' a rubber tube 37 to an eur plug 38,- adapted tobe inserted in thcother'eur, so that thwvi brations at each side on the dia phragm arw utilized; and the equivalent of EU twwphone headeet is obtained, at considerably less costand with greater comfort to the winner and superior sound reception; A stiffening wire 39 having a series of tube embracing coilst) is provided iqJcn thetube.

Themodification of our invention: illustrated imFigs. 3 and 4 consist-s of a loud speaker 4Tp1ovidedwvit1hin a radio receiving cabinetAB, andhaving a sound conduit 49 provided with a flared sound amplifying" chamber 50, this chamber being" provided: along'its forward edge with in series of: out? let tubes 51 to which the elongated individ ual listening tubes 52 are attachedi. The: sound conduit 49 is provided with a control valve 53 for modulating or cutting oli'ithe sound passing therethrough, and atits end with a removable carp which may be re; moved to enable a: listener to hear the sounds: directly from the lotdlmpeaken. 1h control. valve is provided in the throat of thesound amplifying chamber fitlyt'ormodu' lating or cutting ott' the sounds passingtihene through. a a

In Figi there is illustrated a further modification; in: whiclr theoasin 56 offal; loud spealren of the aimpliflying typei Ill ' 57, to which individual listening tubes 58 stance with moist air.

may be attached. In the form' shown in Fig. 6 a sound chamber 59 provided with a series of radial outlets 60 is'placed in the sound tube 61, at its juncture withthe amplifying horn 62.

The modification of the inventionillustrated in Fig. 7 consists of a loud speaker,

in which the sound vibrations at each side of the diaphragm are carried through a single conduit to a sound amplifying chamber. ;.The diaphragm 63 is mounted between a pair of sound box members 6a and 65, the outlets 66 and 67 of which are in communication with the conduits of a pair of conduit members 68 and 69 clamped together and forming ayoke-shaped conduit, the passages at each side of the diaphragm merging into a single passage, at the end of which a sound concentrating chamber 70 having a series of radial outlets 71 is provided. The vibrating lever arm 7 2 is supported by magnetism upon the end of the permanent magnet 7 3,. and extends through an opening 7 k in the conduit member 68 to the center of the diaphragm, and is adapted to be vibrated by a solenoid 75 engaged at its outer end. With this device the vibrations at each side of the diaphragm are carried to the sound chamber 70, and thence to the several list-.

eners through the individual sound tubes 76, connected to the outlets 71.

Our'tubular system may also be used to amplify the sound, depending upon the character of the gases or other sound conductors used to conduct the sound in the tube, as it is well known that gases heavier than air, or moist air, are better sound 4conductors than the ordinary atmosphere and better transmission of sound may therefore be obtained through a tube filled for in- In Fig. 7 we have shown means for carrying out this idea, the tube 76 being provided with an inner lining 77 of moisture absorbing material, as felt.

In hospitals and infirmaries, where a loud speaker would be obnoxious, sound tubes according to our invention could be carried from the loud speaker of a receiving set provided at some central point removed from the patients, to outlets at the costs, making I the reception selective by means for cutting off or modulating the sound. The cost would be very low, considering the number of persons served. 7.

Our invention will change the equipment of a receiving set by mounting one loud speaker, or a receiver, in the receiving set, with outlets to receive one end of each listening tube; dispensing with head-sets, their jacks and leads; and permitting modulation of the sound as desired. 'Long distance stations may be tuned in with less trouble and interference than heretofore, and a more faithful reproduction of the sound is received. The device will operate satisfactorily when the intensit of the sound is insufficient to ordinari y operate a loud speaker.

The cost of head phone sets to accommo what we claim and desire to secure by Letters Patent is:

1. In radio apparatus, areoeiver having a diaphragm, means for vibrating said diaphragm, a sound concentrating chamber element, sound conduit members at each side of said diaphragm extending to said chamber element, and means for conducting sound vibrations from said chamber to the ears.

2. In the art of transmitting sound by radio, a sound receiver, an ear-piece, an 1 elongated tubular member connecting said.

receiver to said ear-piece and means within said tube adapted to render the air there-in moist. v I

3. In the art of transmitting sound by radio, a sound receiver, an ear-piece, an

elongated tubular member connecting said receiver to said ear-piece, and a moisture absorbing inner lining in said tube adapted to render the air therein moist.

4;. In a sound reproducer, a sound box, a diaphragm arranged in the sound box, means for gathering sound reproductions from each side of the diaphragm, a chamber communicating with and receiving the sound from said means, and a plurality of means for carrying sound from said chamber to individual listeners. V

Signed at Waterbury in the county of New Haven and State of Connecticut this 14th day of May, A. D. 1923. r

MARTIN L. MARTUS. EDMUND H. BECKER. JAMES o. BOSS. 

